CHAPTER VI 



THE RESPIRATION 



Experiment i. (Home.) Study of the Throat. — Sit with the back 

 to the light. Study the open mouth and throat with a mirror and make 

 out the uvula, tonsils, and other parts shown in Fig. 68. 



Experiment 2. Anatomy of Lungs. — Study fresh lungs of sheep, 

 hog. fowl, or frog. Will they float ? Will they contract when expanded 

 by air blown in through a quill or other tube? What is the structure 

 of the windpipe? Can you distinguish the arteries from the veins by 

 the stiffness of their walls? Which contain pure blood? Study 

 branching of air tubes. Make a sketch. 



Experiment 3. Tests of Expired Air. — Breathe upon a mirror, bright 

 knife blade, or cold window pane. Result? State your conclusion? 

 Experiment 4 — Carbon dioxid added to limewater will cause a white 

 cloud consisting of particles of limestone. Breathe through a tube or 

 straw or the hollow stem of a reed into clear limewater. Result? Con- 

 clusion? (Limewater may be had at druggist's or made by pouring 

 water upon a lump of unslackened lime and draining it off when lime 

 has settled.) Experiment 5. Breathe for several minutes upon the 

 bulb of a thermometer. Result? Conclusion? Experiment 6. Breathe 

 a few times into a large, carefully cleaned pickle jar, or a bottle. Cork 

 it tightly, and set it in a warm place for several days. Then uncork 

 and smell the air in it. Result? Conclusion? Experiment 7. Pierce 

 a small hole in a card, place card over a wide-mouthed bottle, and 

 breathe into bottle through a tube, lemonade straw, or hollow reed. 

 Pull out straw. Place bottle, mouth downward, on table, and slip out 

 card. Slide bottle to edge of table and lift lighted candle into bottle. 

 Result? Experiment 8. Place bottle of fresh air over lighted candle. 

 Result? Conclusion? (See Animal Biologv, p. 14.) 



Experiment 9. (School.) Testing the Air of a Room. — Fill a fruit 

 jar or large bottle with water, and take it into a room containing many 

 people. Pour out the water. (This insures that all the air now in the 

 jar is air obtained in the room to be tested.) Seal the jar if test is not to 

 be made at once. Test by pouring in two tablespoonfuls of clear lime- 

 water and shake. If the limewater turns milky, the ventilation is bad. 



Experiment 10. (Home and school.) Homemade Current Detector. — 

 Dangle a bit of paper by means of a spider web or thread from the 



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